Fossil fuels will be the primary energy resources to power society for at least the next fifty years. The use of fossil fuels generates CO2. Unfortunately, CO2 is a greenhouse gas, the emissions of which to the atmosphere cause global warming, an alarming threat to humankind. An increased awareness of this problem is recognized in the changes of energy policy at both national and international levels. For the scientific and engineering communities, research activities in searching for means of effectively reducing CO2 emissions has also increased considerably in recent years. This trend will continue for a sustained period of time in near future.
The technical approach to reduce CO2 emissions is simply to avoid the emissions to the atmosphere by capturing and storing it at either pre-combustion or post-combustion stage. At either stage, CO2 has to be separated from either a reducing fuel stream (pre-combustion) or an oxidizing flue gas stream (post-combustion) into a highly concentrated form, from which CO2 can then be further compressed into a liquid form and stored via geologic sequestration. The technologies available for the CO2 separation include primarily mechanical scrubbing and poly-amine solvent-based physical adsorptions. The former is mainly used in separating CO2 from CH4 (or natural gas) and the latter is widely employed in CO2 separation in flue and fuel gas streams of power plants. Unfortunately, both methods are energy intensive and cost prohibitive for large-scale commercial applications. For example, it is estimated that the cost will be at $50-$60 per metric ton of CO2 captured, which translates to $100 million per year for a refinery to invest the CO2 capture technology. Therefore, developing a cost-effective and separation-efficient CO2 capture technology is both scientifically interesting and industrially demanding.
As such, a need exists for a CO2 capture technology that addresses the shortcomings of conventional approaches. Methods of utilizing such technology would also be desirable.